1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device that includes a burn-in test step.
2. Background Art
In the burn-in test performed in a semiconductor manufacturing process, the burn-in test device needs to supply electrical signals to the semiconductor device to be tested. Therefore, the burn-in test device is electrically connected to the semiconductor device through a socket (see, e.g., Japanese Laid-Open Patent Publication Nos. 2004-152495 and 2003-157946).
As semiconductor devices have become more sophisticated, the number of their terminal pins has tended to increase, requiring more socket pins. Furthermore, with the increasing integration density of semiconductor devices, the size of the packages has become smaller. Therefore, there has been a need for a technique for miniaturizing the sockets in order to reduce the size and pitch of the leads and solder balls. As a result, the cost of the sockets has increased.
Further, conventional sockets have been adapted to be electrically connected to all terminals of the semiconductor device through their contact pins; they have as many contact pins as there are terminals on the semiconductor device. When the socket is mounted on a burn-in board, the leads of the contact pins are passed through the through-holes of the burn-in board from the top side and then soldered to the rear side. This means that each burn-in board must be manufactured to have through-holes corresponding one-to-one to all contact pins of the socket. On the other hand, as the number of pins in sockets has increased, so has the number of wires connected to them. Furthermore, the reduction in the contact pin pitch has resulted in a great reduction in the distance between the through-holes. These make it difficult to form appropriate wiring on a burn-in board, resulting in an increase in the cost and manufacturing time of the board.
Further, the smaller the solder balls provided on a package, the more distinct the dents left on these solder balls due to their contact with the socket pins. These contact dents often cause a measurement error in the visual inspection process performed before shipping the product.
BGA packages are likely to suffer these problems, since they have ball terminals. It should be noted that the sockets connected to BGA packages use two types of contact pins: those that maintain contact with a solder ball by exerting a pinching action on it; and those that maintain contact with a solder ball by being pressed against its undersurface. The above contact dent that may cause a measurement error in the visual inspection process is likely to occur especially with sockets using contact pins of the latter type.